Patented new guard keeps your Pinewood Derby® car wheels aligned and secure, race after race. BSA®-exclusive, under-car plate has a ridge that slides right into the pre-cut axle groove to straighten and secure axle to car body. Unique design allows for adequate track clearance and has no interference with car performance. Adds only .2 oz to car weight. WARNING: Choking hazard. Small parts. Not for children under 3 years.